National Electrical Installation Standards

Standards as High as Your Own

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Wednesday, June 15, 2022

Question:

Greetings CQD,

My question pertains to 120V VAVs and HVAC terminal units installed above a non-structural lay-in ceiling. My local AHJ requires that the face of the VAV enclosure cover align with the edge of an opening in the ceiling grid and uses 110.26(A)(3) to determine the "Height of Working Space" for these units measured from the top of the ceiling grid and extending out to the depth of the working space as required by 110.26(A)(1). This creates an "access tile" so to speak, with the VAV enclosure cover aligned with one edge of the opening in the ceiling grid. 110.26(A)(4)(4) seems to override this definition of working space height and the requirement to align the VAV enclosure cover with the ceiling grid. The specific issue that we have run into is when ceiling-supported equipment (i.e. lay-in fixtures, PA speakers, etc) extends above the ceiling grid (any amount) opposite the VAV, the AHJ fails the inspection. I would like a second opinion. Is appropriate to apply 110.26(A)(3) and ignore 110.26(A)(4)(4) in these instances? If I am misinterpreting the code as it pertains to this situation... I would like to be enlightened.

Thanks.

Anon Amous

A

Answer:

Hello Anon and thanks for the question. Section 110.26(A)(4) was incorporated into the NEC to allow practical relief from the other requirements in 110.26(A). When applying this section it should be taken into consideration that there are already space imitations and those should be factored in. Section 110.269A)(4) provides specific about the access openings to the space, the width of the working space, hinged door requirements, and the space in front of the equipment enclosure, meeting the depth requirements of 110.26(A)(1). This is an NEC provision that is treated like an exception to the main rule due to the space limitations, but the installer and AHJ should work together to be on the same page regarding meeting the practical intent. 

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